1. Field of the Invention
This invention pertains generally to the field of cryogenic devices and supporting structure, and more particularly to expansion joints and locks for cryogenic supporting members.
2. Description of the Prior Art
It is often necessary to provide support structure for devices which operate at cryogenic temperatures, examples of which include electrical storage magnets and magnets for fusion reactors. The forces which may be developed by such devices generally must be transmitted from the cold temperature device structure to a warm (room temperature) surrounding support structure. A significant problem is encountered when the devices are cooled down from room temperature to their cryogenic operating temperatures. Such cooling may involve a decrease in temperature of 200.degree. - 300.degree. Centigrade. Since the support structure material will contract when its temperature is lowered, the supporting members of the cryogenically operative devices will undergo a considerable amount of contraction as the temperature of the device is lowered from room temperature to cryogenic temperatures. It is thus necessary to either use materials which undergo very little change in dimension when their temperature is lowered, or to somehow compensate for the decrease in the length of the supporting members. The problem becomes particularly acute when structural materials having differing coefficients of thermal expansion are joined together.